Least invasive surgical techniques have gained significant popularity because of their ability to accomplish outcomes with reduced patient pain and accelerated return of the patient to normal activities. Arthroscopic surgery, in which the intra-articular space is filled with fluid, allows orthopedists to efficiently perform procedures using special purpose instruments designed specifically for arthroscopists. Among these special purpose tools are various manual graspers and biters, electrosurgical devices, and powered shaver blades and rotary abraders. Shaver blades having hollow bores are typically removably coupled to a shaver handpiece and are used for cutting, resecting, boring, and abrading both soft and hard tissue at the surgical site. An arthroscopic abrader (also known as a burr) generally includes a rotatable inner tube having an abrading head at its distal end and fixed outer tube for rotatably receiving the inner tube. Abraders are used for abrading or shaping both soft and hard tissue as bone, cartilage, ligaments, etc. by use of the rotating abrading head. As the tissue is being abraded, debris and fluid are generally drawn or sucked through the rotatable inner shaft which supports the burr.
Requirements for a rotary abrader for arthroscopy include a compact size so as to fit through small cannulae, a means for removal of debris, and a configuration which allows the surgeon to access, while retaining good visibility, structures within a joint. One requirement for good visibility is the effective removal of debris as it is generated. Another is that the instrument be configured so that the view of the active portion of the abrader in contact with the tissue and the view of the tissue being abraded are not obscured by the instrument.
Rotary abraders for arthroscopy generally have a shield, also called a “hood,” on one side of the distal end of the outer tube to prevent inadvertent damage to tissue in close proximity to the tissue being abraded. The distal end of this hood is angled with respect to the tube axis so as to expose only one side of the burr head. During use, the burr head (the abrading element at the distal end of the rotating inner member) is subjected to significant lateral forces. Although rotary abraders typically have a bearing near the distal end of the instrument to support the inner member, lateral deflection of the burr head occurs to some degree. Contact between the burr head and the hood is undesirable since the burr will abrade metal from the hood and deposit metallic debris in the joint. Accordingly, it is necessary to leave adequate clearance between the hood and the burr head. Further, hoods are usually opaque, which hinder visibility of the surgical site during surgery.
Removal of debris from the field is accomplished by aspirating the material from the joint via a lumen in the inner, rotating member which is connected through a means in the handpiece to an external vacuum source. The aspiration of material through the inner member is desirable as this allows easy transfer of the materials from the proximal end of the instrument to the aspiration passage of the handpiece. The manner in which material and fluid enter the lumen at the distal end of the instrument has a large effect on the volume of flow through the instrument and on the frequency with which the instrument clogs. Insufficient flow causes decreased visibility because of residual debris suspended in the intra-articular fluid. Clogging requires that the instrument be removed from the joint and “de-clogged.” The degree of difficulty of clog removal is determined by the instrument design. Even if clog removal is easily accomplished, removing, de-clogging and reinserting the instrument is a nuisance and causes increased procedure times. Aspiration effectiveness, and therefore instrument design, have a large effect on burr efficiency.
There is a need for an improved rotary abrader that provides a clear hood to improve visibility during surgery.
It is accordingly an object of this invention to produce a rotary abrader with a hood or sheath or guard that is available in various shapes to improve the procedure of abrading tissue.
Further, there is a need for an abrading instrument having rigidity, and an aspiration means which effectively removes debris without clogging and which can be readily cleared of clogs without disassembly, and which enhances surgeon visibility in procedures where visibility is crucial, such as SLAP repair.